The concept of arranging a number of sound-producing speakers about a listening area and then selectively distributing an electrical audio signal (monoaural, stereo or quadraphonic) to the speakers is conventional. The concept aims at providing a listener with the sensation of movement of sound about him or her. For example, one such distribution system employs a series of individual coils arranged to have an annular ring rotated therethrough. Each coil is serially interconnected with a corresponding speaker and amplifier. The ring is fabricated of a dielectric material except for a short arcuate section of iron. The ring is rotated, moving the iron slug through the coil and in so doing attenuates the speaker associated with each coil through which the iron slug passes.
Other known sound distribution devices utilize electronic switching or elaborate electronic amplifying techniques to achieve the same results. Representative examples of such sound distribution equipment can be found in U.S. Pat. Nos. 2,832,829, 3,873,779, and 4,002,836.
Unfortunately, systems like those described above and disclosed in the patents are not without certain problems. For example, placing a varying inductance in the signal path connecting the signal source to the speaker tends to introduce distortion into the signal. Further, switching noise can also be imposed when switching the signal from one speaker to another. Some sound distribution techniques require the use of extra power or isolation amplifiers for each speaker for proper impedance matching and operation.